R1:1308a5555fee

Update client logic for inline comment "Save" and "Cancel" actions

Summary: Ref T13559. Substantially correct the client logic for "Save" and "Cancel" actions to handle unusual cases.

Test Plan:
Quoting behavior:

- Quoted a comment.
- Cancelled the quoted comment without modifying anything.
- Reloaded page.
- Before changes: quoted comment still exists.
- After changes: quoted comment is deleted.
- Looked at comment count in header, saw consistent behavior (before: weird behavior).